It is known to incorporate various polymers in a photographic system as mordants, antistatic agents, neutralizing agents, thickeners and sensitizers. However, these polymers, particularly when they are water-soluble, diffuse from a coated layer to an adjacent layer(s) and can adversely affect the properties of a photographic film (e.g., increase fogging, lower sensitivity and cause dye image spreading). To prevent this, mordants are rendered non-diffusable by incorporating therein a functional group reactive with gelatin (as described in U.S. Pat. No. 3,625,694) or by incorporating therein a functional group that reacts with a crosslinking agent (as described in U.S. Pat. No. 3,859,096).
However, the reactivity of functional groups incorporated in mordants of this type is low. Furthermore, it has been difficult to obtain non-diffusable mordants by a reaction with gelatin or a crosslinking agent before diffusion occurs.
Unfortunately, the prior art has not disclosed polymers having incorporated therein a highly reactive functional group that quickly reacts with gelatin or a crosslinking agent to render the polymer non-diffusable.
One technique is known to bind various photographic additives to certain polymers to thereby fix them in a layer where they are added or make them non-diffusable.
The term "photographic additives" as used herein means additives conventionally used in photographic systems such as dyes, dye precursors, development restrainers, development accelerators, couplers, developing agents, auxiliary developer agents, bleaching restrainers, bleaching accelerators, silver halide solvents, silver complexing agents, foggants, anti-foggants, chemical sensitizers, spectral sensitizers, desensitizers, hardening agents, hardening accelerators, gelatin, surfactants, anti-static agents, and the like.
Reactive polymers have been used in diffusion transfer to fix a diffusing dye within a photographic element. For example, mordants as described in U.S. Pat. Nos. 3,709,690, 3,898,088 and 3,958,995, will fix a dye in diffusion transfer. However, these mordants are cationic and fix anionic dyes by mutual electrostatic interaction. Furthermore, their fixing ability is not always satisfactory because it is reduced by water in the photographic system or decreased pH and the fixed dye easily fades upon exposure to sunlight or fluorescent light.
To eliminate these defects, a mordant that will fix certain dyes via covalent bonds is described in U.S. Pat. No. 4,193,795. While this mordant is a good mordant for the specific types of dyes described in British Pat. No. 1,464,104 and U.S. Pat. No. 4,199,355, it is not applicable to other dyes. In addition, the mordant does not fix the dyes at a high enough speed and is difficult to synthesize.
Therefore, the development of a mordant which rapidly and positively fixes diffused dyes, prevents the fixed dye from fading upon exposure to light and which is easy to synthesize on a large scale has been desired in the art.
Further, most photographic light sensitive materials contain gelatin as a component. For example, a silver halide photosensitive emulsion layer, an emulsion protective layer, a filter layer, an intermediate layer, an antihalation layer, a backing layer, a subbing layer on film base and a baryta layer use gelatin as a primary component. These gelatin-containing light-sensitive materials are processed with various aqueous solutions at different pHs and/or temperatures. However, a gelatin-containing layer untreated with a hardener has low resistance to water and is easily scratched after swelling in an aqueous solution. In an extreme case, a gelatin layer may even dissolve out in a processing solution having a temperature of 30.degree. C. or more.
A number of compounds are known to be effective for hardening gelatin and increasing its water resistance, heat resistance and scratch resistance when used in a gelatin layer. These compounds are known as hardening agents used in the production of photographic materials. Examples of such compounds include inorganic compounds such as chrome alum and organic compounds such as aldehyde compounds such as formaldehyde and glutaraldehyde, compounds having an active halogen as described in U.S. Pat. No. 3,288,775, etc., compounds having a reactive ethylenically unsaturated group as described in U.S. Pat. No. 3,635,718, etc., aziridine compounds as described in U.S. Pat. No. 3,017,280, etc., epoxy compounds as described in U.S. Pat. No. 3,091,537, etc., and halogenocarboxyaldehyde such as mucochloric acid. However, these hardening agents have one or more of the following defects: (1) they have an adverse effect on the properties of a photosensitive material (e.g., increase fogging, lower sensitivity or change gradation); (2) cause "after-hardening" wherein the hardening effect changes upon extended storage; (3) are not adequately dissolved in water and cause lack of uniformity of the additives dispersed in the photographic layer; (4) lose their hardening effect depending upon the photographic additive used therewith (e.g., a color coupler for color photosensitive materials); (5) are unstable and do not keep long, or; (6) are difficult to synthesize in large quantities.
A hardener of low molecular weight as is frequently used in hardening gelatin also will diffuse in a gelatin layer so that it is impossible to control the degree of hardening of laminated gelatin layers on a film base. Commonly used polymeric non-diffusable gelatin hardening agents such as dialdehyde starch and polyacrolein are not satisfactory for use in a photosensitive material because they have adverse effects on photographic characteristics, such as increasing fog and lowering sensitivity. The polymeric hardening agents described in U.S. Pat. No. 4,161,407 which have a vinyl sulfone group as an active group cause after-hardening, that is, they harden a gelatin layer only slowly and the degree of swelling Q (defined hereunder) changes with time.
Therefore, the development of a hardening agent that does not cause after-hardening and which does not have any adverse effect on photographic characteristics has long been desired in the art.